Fecal incontinence occurs at least weekly in 3% of U.S. adults and has a significant impact on quality of life. Biofeedback, sacral nerve electrical stimulation (SNS), and anal injection of dextranomer, an inert bulking agent, have been advocated, but absence of studies directly comparing them, and lack of understanding their pathophysiological basis are critical barriers to progress. Our central hypothesis is that biofeedback is more effective, safer, and less costly than dextranomer injection or SNS. We propose a two-step process to address this significant knowledge gap: Step 1 is a U34 planning grant to finalize treatment protocols and confirm access to sufficient numbers of eligible patients, while Step 2 is a U01 multicenter randomized controlled trial (RCT) designed to compare these three treatments using uniform inclusion criteria, design, and endpoints. Specific aims of U34 Planning Years 1 and 2: (1) Finalize procedure manuals. (2) Develop detailed plans for a study management website, electronic symptom diary, data quality checks, and statistical analysis. (3) Develop the safety monitoring plan; NIDDK will appoint Data Safety Monitoring Board. (4) Assess feasibility of recruitment strategy by surveys at all sites. (5) Negotiate agreements with industry for equipment, supplies, technical support. (6) Develop IRB applications and begin ClinicalTrials.gov registration. (7) Recruit, train, and certify biofeedback interventionists. (8) Finalize plans for project governance. Specific aims of U01: (1) Compare effectiveness, safety, and cost of these three treatments in 387 male and female patients with moderate to severe FI who have failed best-practice conservative treatment. The primary measure of efficacy will be >75% reduction in FI episodes compared to baseline. Safety will be measured by number of adverse events, and cost will be measured from both the personal and societal perspectives. Secondary endpoints include validated FI severity and quality of life scales. Outcomes will be assessed at 6, 12, and 24 months. (2) Identify baseline patient characteristics that predict response to each intervention. (3) Identify the mechanistic basis for treatment success for each intervention by comparing pre to post anal sphincter pressures, rectal sensory thresholds, rectal compliance, neurophysiological parameters, and stool consistency. (4) Evaluate treatment combinations. Non-responders by 6 months will be invited to receive one of the other two interventions as additional therapy. (5) Assess predictors of response to conservative treatment and durability of benefits. The study will be conducted by University of North Carolina, Mayo Clinic, Colon and Rectal Surgery Associates of Minneapolis, Georgia Regents University, and a data coordinating center (DCC) at RTI International in North Carolina. Expected outcomes include identifying the best treatment for moderate to severe fecal incontinence that is mechanistically based, durable, and safe. The impact of our project will include new understanding of the comparative effectiveness and safety of three commonly used treatment modalities, a scientific basis for each treatment, and identification of factors that predict clinical outcome.